Method for treating washable goods



United States Patent 4 Claims ABSTRACT OF THE DISCLOSURE Method of inhibiting the growth of staphylococcal bacterial growth on fabric which method comprises contacting the fabric with a washing compound or cleaning agent containing a mixture of the lauryl-pyridinium salt of S-chloro-Z-mercaptobenzothiazole and 2,2-dihydroxy 3,5,6-3,5',6 hexachlorodiphenyl methane.

This is a division of application Ser. No. 840,537, filed Sept. 17, 1959.

The present invention relates in general to a method for providing substantially bacteria-free materials which possess residual antibacterial properties. More particularly our invention is directed to a washing compound containing a mixture of ingredients with substantivity for fabric, which compound will render materials washed therewith substantially bacteria-free and also capable of destroying bacteria subsequently encountered due to the presence of active residual amounts of said mixture of ingredients.

There is an increasing consciousness among the population of the dangers of bacterial contamination and the variety of ways in which the individual can be exposed to bacteria. For example, hospital-acquired staphylococcus infections are no longer looked upon as an isolated problem of the practicing physician or hospital administrator. Rather, the emergence of antibiotic resistant strains of staphylococci and of specific epidemic strains has posed a concurrent threat to hospital populations and the community at large, such that the prevention and control of staphylococcal disease is currently looked upon as a community health problem. With this public awareness, there is an increasing demand for substances which can be effectively used to treat surfaces suspected of past or future exposure to bacteria (particularly staphylococci) in order to control the bacterial population.

One particularly susceptible area for bacterial contamination is clothing, bedding, dishes, glassware, kitchen utensils, etc. Hospitals, hotels, institutions, laundries and the like which deal with large quantities of such washable articles that may be or may become bacterially contaminated could make good use of a compound that could easily be employed in the cleaning of those articles to render them substantially bacteria-free and also resistant to subsequent re-contamination with bacteria.

It is, therefore, an object of our invention to provide a method for producing substantially bacteria-free materials that will be resistant to growth of bacteria subsequently encountered and will also exhibit bactericidal properties thereto.

An additional object of the invention is the provision of an unusually effective antibacterial mixture of ingredients.

A further object is to provide an easy method for bringing articles susceptible to bacterial contamination into contact with our antibacterial mixture to render them substantially free of bacteria.

A still further object is to provide a method for providing dormant antibacterial properties in washable goods, which properties will manifest themselves upon subsequent bacterial contamination of the goods.

An additional object is to provide a washing compound that will incorporate dormant antibacterial properties in articles washed therewith.

Additional objects and advantages will become apparent to those skilled in the art from a reading of the following descriptions of our invention.

Articles subjected to good laundering procedures will be substantially bacteria-free and if protected from contamination prior to use, will remain so until used, However, if not protected prior to use, the article may and probably will become contaminated with bacteria at that time, either through airborne bacteria or contact with personnel handling the articles, and in any event when used will lose its sterility. We have discovered that by washing articles in the manner and with the composition subsequently described it is possible to incorporate into the article a residual amount of antibacterial agent sufficient to keep the article substantially bacteria-free. When treated in the manner we propose, the article not only remains substantially bacteria-free before use without special storage conditions but remains so even after use and actual contact with the virulent bacteria.

The ability of small amounts of the lauryl-pyridinium salt of S-chloro-Z-mercaptobenzothiazole and of 2,2-dihydroxy 3,5,6-3',5',6' hexachlorodiphenyl methane to reduce growth of certain species of bacteria is known. For example, cloth washed with small amounts of 2,2 dihydroxy 3,5,6-3,5',6' hexachlorodiphenyl methane mixed with soap or detergent will reduce the staphylococcal population even when that cloth is deliberately inoculated with massive amounts of a viable staphylococcal bacterial strain. However, in this regard We have noted that in soap used for laundering the lauryl-pyridinium salt of S-chloro-2-mercaptobenzothiazole will allow staphylococcal growth on cloth massively inoculated therewith. Nevertheless, and contrary to the expected result of such a step, we have discovered that a small residual amount on the washed cloth of a mixture of the above two substances results in a remarkable percentage kill of staphylococci, well above that exhibited by use of the previously effective ingredient alone. (For simplicity, the trade designation V-26 will hereinafter be used when referring to the lauryl-pyridinium salt of S-chloro-Z-mercaptobenzothiazole and the trade designation G1l will be used when referring to 2,2-dihydroxy 3,5,6-3',5',6' hexachlorodiphenyl methane.)

While materials laundered with our improved washing compound are no more resistant to contamination during storage than other fabrics, the active antistaphylococcal agents are stable during dry storage of fabrics and subsequent moistening of the fabrics washed in our compound brings the dormant antistaphylococcal activity into play. Thus, as would be expected in a hospital environment when towels, wash cloths, bed linens, and clothing are used by a patient, the fabric becomes contaminated both by contact with the skin of the patient and with the environment itself, When such contamination is accompanied by moisture in the form of perspiration, urine, pus, blood, water or the like, there may be sufficient organic material on the fabric to support the growth of the contaminating bacteria. The active residual concentrations of the mixture of antibacterial agents incorporated in fabrics washed in our laundering compound not only prevent this multiplication but in fact have a dramatic ability to destroy staphylococci on contact. The substantivity of the mixture of antibacterial agents for fabric and their lack of solubility in water is of considerable importance. These characteristics allow the active agents to be fixed to the fabric and they do not leach out during normal use of such things as towels and wash cloths.

The soap product into which our antibacterial mixture is incorporated is somewhat a matter of choice. However, we have found that an especially effective cleaning compound imparting unusually effective antibacterial properties can be produced by mixing the antibacterial ingredients in a built soap. An example of such a soap is one that contains approximately equal major amounts of soap solids and sodium metasilicate together with minor amounts of soda ash, tetrasodium pyrophosphate, moisture and volatile matter and trace amounts of an oil and any of the common optical bleaching agent.

Other suitable washing compounds into which our unusually effective antibacterial compound can be incorporated are dry and liquid detergents and built detergents. An example of an approximate formulation for a dry built detergent would be the following:

Trace amounts of perfume and an optical bleach.

A representative liquid built detergent into which the mixture is effectively incorporated includes:

Percent Potassium pyrophosphate 21 Potassium lauryl sulfate 27 Potassium silicate 5.5 Sodium toluene sulfonate 5 Carboxymethyl cellulose 1 Trace amount of optical bleach. Remainder water.

The antibacterial mixture can also be added to 100% active compounds such as amine condensates and the like.

Extremely small amounts of the residual antibacterial mixture are required, on the order of about 1 p.p.m. to 5 p.p.m. When incorporated in a soap product, we have found a mixture of .25% G-ll plus .25% V-26 based on the weight of the soap to be optimum for depositing the required residual in the washed articles. Lesser amounts can be used with diminishing efficiency. Amounts up to about 1% of each have been found very effective. Greater amounts than this are not increasingly more effective to warrant the added expense.

The length of time that an article is subjected to the antibacterial-containing mixture is unimportant so long as there is actual contact of the article with the antibacterial agent. While we do not wish to be limited to any particular theory as to how the antibacterial agent acts, it appears that at least insofar as cloth is concerned it is at least partially substantive to the cloth and it actually becomes embedded in the cloth fibers since it exhibits a residual antibacterial effect after the cloth has been washed. A 1 p.p.m. residual of our antibacterial mixture is suflicient to render cloth substantially free of viable bacteria.

The following data is presented to illustrate our invention only and should not be construed as imposing limitations on the scope of the invention apart from those delineated in the appended claims.

For test purposes, a mixture of five different strains of coagulase positive Staphylococcus aureus recently isolated from patients with staphylococcal disease were utilized. Results on all test procedures with wild type staphylococci (i.e. those not grown under controlled laboratory conditions) have been similar when FDA strain 209 was used as the test organism.

EXAMPLE I Four test tubes were prepared as follows: two were inoculated with one million actively growing staphylococcal organisms per 10 ml. of trypticase soy broth and two were inoculated with ten million organisms per 10 ml. of the nutrient broth. To one of each group of tubes was added 1 p.p.m. (.0001%) by weight, of an equal mixture of 6-11 and V26. To the other tube in each group was added 5 p.p.m. (.0005%) by weight of the mixture. The tubes were incubated for 72 hours at 37 C. At this point our results show complete inhibition of staphylococcal growth in the nutrient medium. Subsequently, subcultures from each of the tubes into trypticase soy broth containing no antibacterial agents, and following incubation, failed to show growth of the original inoculum. These results indicate a bacteriocidal as well as a bacteriostatic effect.

EXAMPLE II Seven one-inch squares of cloth were inoculated with a mixture of five different strains of coagulase positive staphylococci organisms. Bacterial counts were made after inoculation. The cloths were then separately washed ten times in an automatic washing machine with a built soap product containing the amounts of added ingredient as shown in the following tabulation. The results of the washing treatments were as follows:

Bacterial Count Ingredient No Kill Original After 16 Hour Incubation Control No additional 25,000,000 1,500,000,000 0 ingredient. Cloth 1 0.1% G11 130,000,000 120,000,000 7 Cloth 2 0.5% G-11 130,000,000 56,000,000 56 Cloth a 0.2% V-2e 15,000,000 220,000,000 0 Cloth 4 0.5% v-20 32, 000,000 00, 000, 000 0 Cloth 5 gj 28, 000, 000 17, 000, 000 40 Cloth s sj 240, 000 1, 000 99. s

1. The washed cell method This procedure involves the inoculation of cloth (washed both with soap containing our mixture and with an untreated soap) with a 0.1 ml. inoculum containing one to five million organisms per 0.1 ml. of washed cells of staphylococci.

The Washed cells are prepared by centrifuging a 16- hour incubation trypticase soy broth culture of staphylococci for ten minutes. The cells are then suspended in saline solution. This operation is repeated three times to remove all the nutrient material from the suspension before inoculating the cloth. Subsequent to inoculation, the cloths are held in a humid atmosphere to prevent evaporation of moisture. A determination of the number of staphylococci placed in the cloth is made before and after holding for a period of time at 37 C. Under these conditions one of two results may occur: (1) the inoculated staphylococci may survive the treatment or (2) as a result of the activity of antibacterial agents, they may be destroyed. In no case will growth occur, since organic materials in the broth have been removed. This test measures antibacterial residues. It thus evaluates situations which would exist in a hospital wherein a patient periodically uses a wash cloth or a towel with subsequent hanging to dry the cloth.

2. The contact plate method This procedure involves inoculation of the surface of a sterile agar medium with a mixture of staphylococci. A 1 square inch test cloth ((a) unwashed, (b) washed in a base soap, (c) washed in soap containing our antibacterial mixture) is placed in the center of the plate. The plate is then incubated at 37 C. for 18-24 hours. Antibacterial activity in the cloth, as measured by this test, is indicated by inhibition of growth under the cloth. The marked insolubility of our antibacterial mixture in water is reflected in this test by the failure to observe large zones of inhibition surrounding the test cloth. The effect noted when using this procedure is indicative of inhibition and does not necessarily measure killing activity. The stuation, however, parallels the situation that exists in the presence of fabric contaminated with organic material such as pus, blood, urine and food.

3. Culture inoculum method In this process three 1 inch squares of cloth having been washed with soap containing our antibacterial mixture are inoculated with 0.1 ml. of a 16-hour broth culture of staphylococci. The culture is diluted with tripticase soy broth so that each square inch of cloth is seeded with about 500,000 organisms. One of the 3 squares is analyzed immediately after being inoculated to determine the number of organisms present. The remaining two squares are placed in petri dishes having asbestos liners in the covers which are kept moist, and are incubated at 37 C. in a desiccator. One square inch is removed after 8 hours of incubation and the other after 16 hours, and a plate count made. Three other one inch squares of cloth washed in soap not containing our antibacterial mixture and inoculated as above, are used as a control. Residual antibacterial properties are then determined by comparing counts obtained in the treated and untreated cloths after 0, 8, and 16 hours incubation.

EXAMPLE III This test was made to determine the minimum residual necessary to obtain bacterial control with our mixture. The culture inoculum method was used and results evaluated as follows:

Test 1 p.p.m. residual Control No additional 1 1- V-26 Ingredient Indicates bacterial growth. Indicates no bacterial growth.

EXAMPLE IV WASHED CELL METHOD Staphylococci per Material square inch Contact plate method Initial 16 hours Diaper 3, 900, 000 1, 000 Oompelte inhibition.

1, 000 D0. 2, 500, 000 2, 500, 000 N 0 inhibition.

Diaper Diaper (control) By the use of the phrase substantially free of bacteria we do not intend to convey the meaning that no bacteria will ever be present. What is meant is that the vast majority of bacteria will be removed from the materials during the washing operation. Certain heatresistant spores may survive and remain on the washed goods. Nevertheless, for all practical purposes the material out of the washer will be substantially free of bacteria. However, when the material (for example a sheet) that has been washed with a soap containing our antibacterial mixture is further contaminated (as for example from the environmental air, contact with contaminated storage facilities, contact with a hospital patient, etc.) and is subsequently moistened in some manner, the residual antibacterial activity imparted to the cloth will destroy the bacteria present.

Obviously many modifications and variations of the invention as hereinbefore set forth may be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.

We claim:

1. A method of inhibiting the growth of staphylococcal bacteria on fabric which comprises contacting the fabric with a water solution of a washing compound containing as the essential antirbacterial ingredients a small but effective amount of the lauryl-pyridinium salt of S-chloro- Z-mercaptobenzothiazole and 2,2-dihydroxy 3,5,6-3,5,6' hexachlorodiphenyl methane such that after the fabric is dried, a residual amount in the order of about 1 p.p.m. to about 5 p.p.m. of a mixture, in the ratio of about 1:4 to 4:1 parts by weight, of lauryl-pyridinium salt of 5- chloro-2-mercaptobenzothiazole and 2,2-dihydroxy 3,5, 6-3',5',6' hexachlorodiphenyl methane is present on the fabric.

2. A method of inhibiting the growth of staphylococcal bacteria on fabric comprising cleaning the fabric with a cleaning solution containing as the essential anti-bacterial ingredients a small amount of a mixture of about equal parts by weight of lauryl-pyridinium salt of 5-chloro-2- mercaptobenzothiazole and 2,2'-dihydroxy 3,5,6-3',5',6 hexachlorodiphenyl methane such that a residual amount in the order of about 1 p.p.m. to about 5 p.p.m. of the mixture remains on the fabric.

3. A method of inhibiting the growth of staphylococcal bacteria on a fabric comprising washing the fabric with a hot water solution of a washing composition as the essential anti-bacterial ingredients containing a mixture of between about .25%-1% by weight of the lauryl-pyridinium salt of 5-chloro-2-mercaptobenzothiazole and between about .25 %1% by weight of 2,2'-dihydroxy 3,5,6-3',5,6' hexachlorodiphenyl methane, removing the washing composition and drying said fabric whereby about 1 p.p.m. to about 5 ppm. of the mixture remains substantive to the cloth.

4. The method of claim 1 wherein the washing compound contains approximately equal major amounts of soap solids and sodium metasilicate, minor amounts of soda ash, tetrasodium pyrophosphate, moisture and volatile matter, and trace amounts of an oil and chemical bleaching agent.

References Cited UNITED STATES PATENTS 2,409,718 10/1946 Snell et a1 252106 X 2,535,077 12/1950 Kunz et al. 252-107 2,555,024 5/1951 Brooks 252106 2,633,446 3/ 1953 King 167-84 2,879,200 3/1959 Kosmen 16733 2,898,264 8/1959 Weber 252107 2,948,684 8/ 1960 Thiele 252-107 FOREIGN PATENTS 792,538 3/ 1958 Great Britain.

MAYER WEINBLATT, Primary Examiner.

US. Cl. X.R. 

